A Houma towing and tugboat magnate has pleaded guilty to using his personal and business accounts to funnel campaign contribution checks in the names of others to the campaigns of Democratic Sen. Mary Landrieu and Republican Sen. David Vitter in 2008.

The plea by Arlen "Benny" Cenac Jr. was announced Wednesday by Acting Assistant Attorney General Mythili Raman of the Justice Department's Criminal Division and U.S. Attorney Dana Boente.

Cenac, 57, a resident of Houma and the president and owner of Cenac Towing, pleaded guilty to making false statements to the Federal Elections Commission. He faces a maximum penalty of five years in prison when he is sentenced Sept. 5, 2013, before U.S. District Judge Carl Barbier.

"Today's plea marks the second campaign finance conviction in a week and is one of many such cases brought throughout the nation," Raman said. "Mr. Cenac's crime undermined the cornerstones of campaign finance laws, and his conviction demonstrates our resolve to hold accountable anyone who corrupts our electoral process."

The announcement did not name the senators or cite the total dollar amount that Cenac gave illegally.

But last August, Cenac and his company agreed to pay a $170,000 fine for using corporate funds in 2008 to funnel $40,000 in illegal contributions to the campaigns of Landrieu and Vitter.

At the time, it was the largest fine of 2012 levied by the Federal Election Commission, and the 34th in the commission's history, according to Citizens for Responsibility and Ethics in Washington. The watchdog group filed the complaint that triggered the investigation.

"Mr. Cenac, in an effort to increase his political contributions, structured his financial transactions and created false documents," Boente said. "This prosecution should serve as a warning to people who attempt to hide their identity and make contributions in excess of legal limits."

The plea documents say Cenac obtained cashier's checks using his personal and corporate funds in names of other individuals, including people he knew professionally, personally or through family relations. Cenac did not seek or get the permission of the individuals he listed on the cashier's checks, the documents say. He then submitted the checks as campaign contributions to the campaigns of the two U.S. Senate candidates, causing the campaigns to submit false information regarding the source and the amount of the contributions to the FEC.

According to the FEC, Cenac wrote a check to buy $15,000 in cashiers checks at Whitney National Bank in the names of six couples. Those checks, the FEC said, were handed over to the Vitter for Senate campaign.

In April 2008, the FEC said, Cenac wrote a personal check for $23,300, and his secretary purchased cashier's checks with it, also for six couples. Those checks went to the Landrieu Senate campaign, also as political contributions.

The FEC said Landrieu's campaign was suspicious about the sequentially numbered checks and decided not to accept the contributions, sending the money on to the U.S. Treasury.

A Vitter spokesman said the senator later donated the $15,000 to charity -- split between Angels' Place and the Cancer Association of Greater New Orleans.